1. Field of the Invention
This invention relates to washing textiles and more particularly refers to a new and improved process, and apparatus therefor, for washing laundry in an automatic washing machine.
2. Description of the Prior Art
Up to now washing process for textiles in automatic washing machines consumed considerable amounts of water, energy and washing agents, and their wastes contributed to a great extent to the pollution of the environment.
In the known washing processes for heavy and white laundry, before each wash process, commercial washing agents are introduced into compartments which are provided for this purpose in the machine. According to conventional instructions by washing machine manufacturers, approximately 140g of a washing agent are provided for each soak and wash period (i.e. in washing machines for 4 kg dry wash with approximately 20 l (liters) of liquid mixture (7g/l in the soak period and approximately 7 g/l in the wash period). During the wash period, the liquid mixture is heated to approximately 50.degree. C and in some cases the washing drum is moved back and forth at this temperature. Thereafter, the wash solution is siphoned off and fresh water is added and again approximately 140g washing agent is introduced from the storage chamber and the main washing operation is carried through, whereby the liquid mixture is usually heated to between 90.degree. and 95.degree. C, under a reversing motion and the drum is kept in motion at this temperature for another 10 to 15 minutes. Thereafter, the machine is filled with fresh water for a higher mixture ratio and the laundry is rinsed in up to seven rinse cycles from 2 to 5 minutes each, with a water change for each cycle, in order to remove remaining washing agents and to disperse the dirt. For achieving a soft laundry, water softeners may additionally be added to the last rinse.
The known methods for washing are usually performed in automatic washing machines in which a drum is rotatable and horizontally positioned in a tank, whereby the drum serves as container and agitator for the laundry. As a rule, an electric motor is used for driving the drum.
Such washing machines are provided usually with so-called wash agent containers consisting of two compartments which are filled by the user with the required amount of washing agents before beginning the washing process. In machines with wash-agent containers with several compartments, a provision is usually also made for a commercial water softener. The compartments of the washing agent container, are connected with the fresh water supply of the machine by electrically controlled valves and on the other side, with an input channel to the tank.
Furthermore, the known automatic washing machines contain a program selector switch for the setting of the desired program depending on the type of laundry to be washed and its degree of dirtiness, and also a program control device in which, by mechanical and/or electrical means, the corresponding wash programs are stored so that, by its operation, the various functions, namely water admission, heating, laundry agitation and draining, are controlled in the desired sequence. The mentioned functions are additionally influenced by temperature and water level measuring devices.
For the removal of the liquid which is no longer needed in the tank, a drain opening is generally provided at the lowest point, which communicates over a drain pump and a riser tube into a discharge tube and drain.
The performance of the known wash processes for textiles in automatic washing machines is usually done with commercially packaged washing agents. These washing agents in powder form contain mainly the following active substances: active wash components, principally surface-active agents, complex alkali phosphates as main structural components, alkali-perborates as bleaches and also silicates as alkali carriers and bleach agent stabilizers.
Though the packaged commercial washing agents which are used at the beginning of the washing process have a very good washing effect, their use causes some of the disadvantages of the up-to-now known wash processes which are carried out in washing machines.
Usually, the content of complex phosphates in packaged commercial washing agents is set so high that it is sufficient for very hard water (ca 20 .degree. dH).
However, according to statistics only approximately 60% of the households in the German Bundesrepublik wash with water over 15.degree. dH (SOFW 20/1961, pages 621 to 637. H. Oxe) which means that about 40% of the German households are residing in areas with typical soft water. Consequently, in these households the washing is either done with an overdose of phosphates and an unnecessary waste of material or, if one stays within the recommended dosage for low water-hardness areas, the washing process is carried out with an underdose of detergents and unclean laundry will result.
Add to this the fact that, though the washing agent manufacturers print on their packages recommendations for the dosage according to general experience, there is a tendency to overdose the washing agent when adding it by hand, which results in detrimental effects to the environment.
Furthermore, the statistics reveal (SOFW 19/1974, page 491 in conjunction with the Handbook for textile engineers and textile technicians "Grundlagen der Textilveredlung" part I 61, page 21) that washing agents for fine laundry are used in a considerably lesser amount compared to the amount of actually existing fine laundry. Thus the overwhelming part of fine laundry is washed, in practice, with washing agents for heavy laundry.
However, in the known washing methods with a washing temperature of up to 60.degree. C the bleaching agents (perborates) and their stabilizers, which make up approximately 30% of a general purpose washing agent or full washing agent, are not utilized since they can only become active at temperatures far above 60.degree. C. Thus, also in the case of fine laundry, generally an excessive amount of chemically active substances is used and the environment is polluted as a result thereof.
Furthermore, it is known that due to the general habits with respect to handling laundry in most households, a full washing agent is also used in the soaking process. However, in the soaking process too, the high portion of bleaching agents, which is up to 30% in a full-washing agent, is not effective because of the lower temperatures and therefore leaves the washing process in an unutilized state. Thus, in this case too, an excessive amount of active substances is used and the environment is additionally polluted.
Even when washing in temperatures up to boiling, a considerable portion of the perborates goes unused into the drain water. One of the reasons for this is that the manufacturers of general purpose washing agents must set the proportion of bleaching agents for the highest possible spot cleaning efficiency. However, as can be learned from the literature (Trace Elements in the Environment, Advances in Chemistry, Series 123, Page 135) a relatively high boron content in natural waters can have a detrimental effect on the growth of some plants. It must also be considered that the maker of pulverized general purpose washing agents, generally uses alkali-perborates since the other known bleaching agents are less suited for this purpose.
The usage of perborates entails other disadvantages in addition to the above-mentioned ones. First, it is necessary to heat the washing mixture far above 60.degree. C for bleaching purposes, since the dissociation of perborates begins with slow speed only above 60.degree. C and only at approximately 90.degree. to 95.degree. C does dissociation rapidly take place so that an effective bleaching process is carried out. This makes it necessary to carry out the washing process for white laundry at 95.degree. C, since washed, but an unbleached white laundry is not considered as clean.
However, a maximum temperature of 60.degree. C of the washing mixture would be sufficient for the removal of the dirt and its dispersion to so fine a distribution that a re-depositing onto the washed fabric does not occur.
The use of complete all purpose washing agents for washing with bleaching, thus requires a high washing temperature. Therefore, a high energy consumption relative to the wash effect is required.
Finally, the high water consumption of the up to now practiced washing processes must be considered.
The manufacturer of washing machines has to make sure to provide in the automatic sequence of the conventional wash process a sufficient number of rinse cycles so that the remaining alkali content cannot result in damage to the fabric or be a skin irritant. This is particularly important because overdosing of the washing agent by adding it by hand frequently occurs.